Conventionally, lubricants are used in various mechanical machines so as to reduce friction coefficients of sliding mechanisms. The reduction of the friction coefficient of the sliding mechanism by improvement of the lubricant leads to not only increases in operation efficiency and part life but also decreases in noise and vibration.
There is, for example, disclosed a liquid lubricant composition that contains nanoparticles and, when applied to a steel sliding part of an internal combustion engine, can reduce a friction coefficient of the sliding part significantly for improvement in fuel efficiency (see Patent Document 1).
On the other hand, there is disclosed a grease for a constant velocity joint that contains a solid lubricity additive such as molybdenum dithiocarbamate (MoDTC), which is known as one example of organic molybdenum additive, and, especially when applied to a constant velocity joint of a vehicle drive shaft, can reduce noise caused by structural parts of the joint (see Patent Document 2).